142 ANNUAL OF SCIENTIFIC DISCOVERY. 



LIGHTING BY ELECTRICITY. 



During the past summer, in the prosecution of some public works at 

 Paris, it was thought expedient to urge the work by night, as well as day, and 

 the aid of the electric light was resorted to with great success. M. Regnault, 

 who took charge of the lighting, communicates to the Comptes Rendus 

 the following statement of the expense. The apparatuses, which worked 

 regularly with great success for four consecutive months, were composed 

 each of a battery of fifty Bunseii elements of large size. 



The expense per day was as follows : 



Wages of the workmen, ..... 4.50 francs. 



Mercury v 5.00 " 



Zinc, ......... 4.oO " 



Charcoal points, . . . . . . .1.50 " 



Nitric acid 1.80 " 



Sulphuric acid, 1.84 " 



Totals, 19.04 $3.80 



Two sets of apparatus being employed, the expense of lighting 400 

 workmen was then 38.08 francs $7.62, per evening, or 1.9 cents per man. 

 The economy is considerable, and the work can be done without danger, 

 and with a regularity which cannot be obtained by any other means. 



ON THE ARRANGEMENT OF LIGHTNING CONDUCTORS. 



At the British Association, Mr. Kasmyth described a Lightning Con- 

 ductor for Chimneys, which he conceived affords more perfect insulation, 

 and is therefore safer, than those in common use. The present practice is 

 to fix the conductor outside the chimney by metal holdfasts, by which 

 means during severe thunder-storms chimneys are often damaged by the 

 lightning entering at the points of attachment and displacing the bricks. 

 In the method of fixing the conductor recommended by Mr. Nasmyth, the 

 metal rod is suspended in the middle of the chimney by branching sup- 

 ports fixed on the top. A conductor of this kind had proved efficient 

 in storms which had severely injured other chimneys in the neighborhood 

 that were protected in the usual manner. An experience of eighteen years 

 had tested the superiority of the plan. 



Prof. Farraday, on being called on for his opinion, said that he recom- 

 mended that lightning conductors should be placed inside instead of out- 

 side of all buildings. He had been consulted on that point when the 

 lightning conductor was fixed to the Duke of York's Pillar, and he ad- 

 vised the placing it inside ; .but his advice was not taken, and the rod was 

 fixed outside, to the great disfigurement of the column. All attachments 

 of metal to or near the conductor are bad, unless there be a continuous 

 line of conduction to the ground. He mentioned the instance of damage 



